Electric glass-annealing furnace



0. A. COLBY.

ELECTRIC GLASS ANNFALING FURNACEv APPLICATION FILED APR- 7. I920.

1,401,674, Patented Dec. 27; 1921'.

WITNESSES:

INVENTOR b. BYGraACoIy ATTORNEY uNrr o STATES PATENT OFFICE.

ORA A. COLBY, or IRWIN, PENNSYLVANIA, nssreNoa ro WESTINGHOUSE nmcrmc a MANUFACTURING comrm, A CORPORATION or IENNSYLVANIA.

ELECTRIC GLASS-ANNEALING FURNACE 'Application filed. April 7,

T all whom it may concern. Be it known that I, ORA A. COLBY, a citizen of the United States, and a resident of Irwin, in the county of Westmoreland and State of Pennsylvania, have invented a new and useful Improvement in Electric Glass- Annealing Furnaces, of which the followa specification.

invention relates to electric furnaces and particularly to furnaces of the electricresistance type and it has for one of its ob jects to provide an electric-resistance furnace for annealing glass objects which shall have a relatively low rate of'deterioration of the resistor and which may be operated for comparatively long periods of time at a relatively high temperature.-

Another object is to provide a furnace of this type with a resistor comprising solid blocks of refractory electrical-conducting material which shall be so located relative to each other as to cause a higher temperature at one end of the annealing chamber than will exist at the other end thereof.

Another object is to" provide a construction for a furnace of the character indicated which shall permit of combining a. number of such furnaces in a relatively small space, thus increasing the heat efii- ,ciency of the individual furnaces and having a relatively small number of terminal electrodes to conduct the current to and from all of the resistors.

In practising my invention, I provide one or more annealing chambers in a refractory casing, a plurality'of resistance blocks of solid refractory electrical-conducting mate rial located in each of the chambers and constituting the top and bottom walls thereof,

The-supporting structure of the furnace comprises an exterior metal casing or frame 1 in which is built an outer shell 2 of heatinsulating brick and an inner shell 3 of Specification of Letters Patent.

1920. Serial No. 372,019.

ter of the furnace to form a chamber 4. In

the drawings, I. have illustrated a double back-to-back furnace but this is not essential and the furnace may comprise one, two or even four such chambers when a furnace structure of substantially rectangular or circular cross-section is used, it is to be noted that the heat'efficiency of two or of four such operating chambers combined into a single structure is higher than when only one operating chamber is used because the exterior radiating surface of the combined structure is relatively small with a larger number of operating chambers.

The resistor in eachof the chambers 4 comprises two blocks or slabs of solid refractory electrical-conducting, material such as carborundum or silicon-'carbid, these Patented Dec. 27, 1921.

blocks being placed in a substantially horiedges of the two blocks are somewhat closer together than the front edges thereof. A mass 6 of plastic,material, such as a mixture of crucible clay and graphite with a suitable binder, is provided in each of the chambers 4 to hold the resistor blocks 5 in their proper relative positions. The mixture 6 is, of course, changed to a substantially solid refractory condition as soon as the furnace is placed in operation. A cover member 7 closes the front side of each of the chambers 4 and is provided with a central opening 8 through which a glass object, such ,hoppers 10 and is of relatively larger crosssection than the electrode 11 so that it conducts the current from the electrode 11 to the resistor blocks 5'with a relatively small drgp in voltage and, therefore, with a. relatively small amount of heat generated therezontal position and so located that the rear r as a lamp chimney 9, may be introduced and I claim as my invention' z i" 1 1. .In an electric furnace, tliecombina'tion" 'with a chamber, of a pair of resistor blocks in: The finely divided granular material operatively engages the terminal electrode 11 and the resistor blocks 5 and provides a large number of contact paths through which the current may flow from one to the other. Some oxidation of this granular materialtakes place during the operation of the furnace but, as the hopper 10 is open at its upper end, the granular materialmay be easily repacked by means of a suitable stirring rod. Whenever required, the material to replace that which is consumed may be easily placed in the hoppers 10. A slab 15 of a suitable highly refractory material, such as carborundum, is placed between the resistor blocks 5 adjacent each of the hoppers 10 and prevents the granular material 14 entering the annealing chamber proper.

It is to be understood that any suitable arrangement of metal terminal plates l2-and connections to the electrical. supply circuit conductors 13 may be used as desired and that the sets of resistor blocks 5 in a plurality of furnaces may be connected either in parallel or in seriescircuit relation, as ma be suitable or desired.

thus provide an electric-resistance 'fur- 'nace for annealing glass articles in which" the resistor comprises solid blocks of refractory electrical-conducting material which may operate for relatively long periods of time with relatively small deterioration and in. which the-method of conducting the current to and from-the resistors insures that the furnace may be operated for relatively long'periods of'time and-still obtain good operative connection with the resistor blocks."

While I have shown a specific embodiment of my invention, various-changes may be made therein without departing ,from the spirit and scope of my invention, and I desire that only such limitations shall '*be placed thereon as are imposed by the prior art or are specifically set forth in the appended claims;

of solid refractory electrical-conducting material constituting the top and bottom walls of said chamber, the adjacent faces of said blocks beingslightly divergent outwardly,

means for holding said blocks in their operative positions,'means for conducting current to and from said resistor blocks, and a cover member for 'said chamber having a central opening for the insertion of material to be heated.

2. In an electric furnace, the combination 'with a chamber, of a'resistor comprising,

solid blocks of refractory electrical-conducting material constituting the sloping top and bottom walls of said chamber, means for holding said resistor blocks in their operative positions, hoppers adjacent the ends of walls of said chamber, said blocks being so located relative to each other that the temperature at the rear of the chamber is higher than that at the front of said chamber, means for holding said resistor blocks in vtheir operative positions, hoppers opposite the' ends of said'resistor blocks, solid carbonaceous terminal electrodes located in said hoppers, masses of electrical-conducting granu-j lar material interposed between said elec-' trodes and said resistor blocks, said masses of material being of greater cross-section than the resistors to prevent over-heating of the electrodes, and a cover member for the front of said chamber comprising a solid block of refractory material having a central opening for the insertion of the material to be heated.

4. In an electric furnace, the combination with a plurality of spaced' chambers, of a material constituting the top. and bottom to eachother that the temperature at the rear of the chamberis higher than at'the (front thereof, means adjacent each chamber 1 for holding said resistor blocks "in their' operative positions, hoppers opposite v the ends'of said resistor blocks, solid carbonaceous electrodes extending into said hoppers, masses of electrical-conductin granular material iii-said hoppers and a apted to conduct current from 'said electrodes to said resistor blocks, and a cover member for the front of each of said chambers comprising a solid block ofrefractory material having a central opening for the insertion of ,the material to be heated.

'In testimony whereof, I have hereunto subscribed my name this 30th daylof March,

ORA A; cofLBY,

resistor for each chamber, com rising solid blocks 'of refractory electrica -conducting,

100 walls, saidl blocks being so located relative 

